xen/pci:use hypercall PHYSDEVOP_restore_msi_ext to restore MSI/MSI-X vectors

.. to use the new hypercall to restore the vectors for MSI/MSI-X devices.
If the new hypercall fail, we will call the old one (PHYSDEVOP_restore_msi).

[v1: Attempt only once to make the new hypercall, not everytime]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Liang Tang <liang.tang@oracle.com>
diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 9eea4ed..4521b05 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -248,6 +248,8 @@
 }
 
 #ifdef CONFIG_XEN_DOM0
+static bool __read_mostly pci_seg_supported = true;
+
 static int xen_initdom_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 {
 	int ret = 0;
@@ -308,12 +310,27 @@
 static void xen_initdom_restore_msi_irqs(struct pci_dev *dev, int irq)
 {
 	int ret = 0;
-	struct physdev_restore_msi restore;
 
-	restore.bus = dev->bus->number;
-	restore.devfn = dev->devfn;
-	ret = HYPERVISOR_physdev_op(PHYSDEVOP_restore_msi, &restore);
-	WARN(ret && ret != -ENOSYS, "restore_msi -> %d\n", ret);
+	if (pci_seg_supported) {
+		struct physdev_pci_device restore_ext;
+
+		restore_ext.seg = pci_domain_nr(dev->bus);
+		restore_ext.bus = dev->bus->number;
+		restore_ext.devfn = dev->devfn;
+		ret = HYPERVISOR_physdev_op(PHYSDEVOP_restore_msi_ext,
+					    &restore_ext);
+		if (ret == -ENOSYS)
+			pci_seg_supported = false;
+		WARN(ret && ret != -ENOSYS, "restore_msi_ext -> %d\n", ret);
+	}
+	if (!pci_seg_supported) {
+		struct physdev_restore_msi restore;
+
+		restore.bus = dev->bus->number;
+		restore.devfn = dev->devfn;
+		ret = HYPERVISOR_physdev_op(PHYSDEVOP_restore_msi, &restore);
+		WARN(ret && ret != -ENOSYS, "restore_msi -> %d\n", ret);
+	}
 }
 #endif
 
diff --git a/include/xen/interface/physdev.h b/include/xen/interface/physdev.h
index 44aefa9..9818456 100644
--- a/include/xen/interface/physdev.h
+++ b/include/xen/interface/physdev.h
@@ -205,6 +205,14 @@
     uint32_t pirq;
 };
 
+#define PHYSDEVOP_restore_msi_ext       27
+struct physdev_pci_device {
+	/* IN */
+	uint16_t seg;
+	uint8_t bus;
+	uint8_t devfn;
+};
+
 /*
  * Notify that some PIRQ-bound event channels have been unmasked.
  * ** This command is obsolete since interface version 0x00030202 and is **